Studies will be continued on the hormonal control of growth and development using insect metamorphosis as a model system. Using our radioenzymological assay for ecdysone monoxygenase activity (the prohormone ecdysone at 60 Ci/m mol is converted to the molting hormone, 20-hydroxyecdysone and the latter purified and radioassayed), we will further explore the control of this critical mitochondrial cytochrome P-450 enzyme by juvenile hormone and neural factors. The possible induction of this enzyme by well-known inducers of microsomal P-450 activity (e.g. phenobarbitol). The action of juvenile hormone will be probed by examining the relationship between very specific hemolymph (blood) binding proteins and target cell receptors using the competitive binding techniques we perfected (dextran coated charcoal, hydroxylapatite, etc). We will also attempt to purify the two major forms of the brain neurohormone (PTTH) that initiates the molting cycle by stimulating the prothoracic glands to synthesize and secrete ecdysone. Assay of activity will be by our recently devised specific and highly sensitive in vitro assay and purification will include techniques routinely used in this laboratory, i.e. gel filtration chromatography, gel electrophoresis, isoelectric focusing and high pressure liquid chromatography. Using organ culture techniques we will continue our investigation of the mechanism by which PTTH activates the synthesis of ecdysone via cyclic nucleotides. Protein kinases and phosphorylated proteins will be analyzed in active and inactive prothoracic glands and in inactive glands stimulated by PTTH. These studies on the three major insect growth hormones should provide a basis for examining the means by which animals regulate and maintain hormone titers and how environmental cues are transduced into endocrinological events. Endocrine related diseases are well known and in many cases result from a failure of homeostatic mechanisms (i.e. regulation of hormone titer). In addition, these studies could lead to new concepts for insect control and this group of animals act as vectors of innumerable diseases (e.g. malaria, encephalitis, etc) and are indirectly responsible for diseases resulting from malnutrition.